yes, you execute the command in a shell. Do so just prior to running the bluefish configure script.
I've been thinking about this - it might be worth checking whether the variable has already been set, before you 're-set' it. From the command line, issue -
If anything is returned, instead of resetting the variable, you can append the path you want to include to the existing path by issuing -
Hope this makes sense. But I think that the variable probably isn't set at the moment.